1. Field of the Invention
The present invention relates to a modular shelving unit, and particularly a modular shelving unit including posts each formed by interconnecting a plurality of tubular members together.
2. Discussion of the Background
FIGS. 14 and 15 illustrate the modular shelving unit of a well-known type, which includes four upright posts 51, spacers 53 respectively attached on the posts 51, and a shelf 52 detachably supportable by the posts 51 via sockets 54 provided at respective corners of the shelf adapted for respectively fitting around the spacers 53 on the posts 51.
The posts 51 each include a plurality of tubular members 55 interconnected together via interconnecting members 56 each having outwardly threaded portions 57 at its upper and lower end portions. The inner circumferential wall of each tubular member 55 forms an inwardly threaded portion. The interconnection of adjacent tubular members 55 is accomplished by threaded engagement between the outwardly threaded portions 57 of the interconnecting member 56 and corresponding inwardly threaded portions of the tubular members 55. The interconnecting member 56 is provided on the outer circumferential wall between the opposite end portions thereof with a flange-like stopper 58 which is interposed between the abutting edges of the tubular members 55 and is exposed to the outside when the adjacent tubular members are interconnected together.
The above prior art arrangement has a drawback that a relatively heavy load caused by an object placed on the shelf 52 concentrates mainly into the stoppers 58, causing an excessive load over the stoppers 58. This may result in a slight deformation of the posts 51 around the interconnecting members 56.
For the modular shelving unit with posts 51, each of which forms axially spaced annular grooves 59 in the outer circumferential surface thereof, the spacer 53 is adapted to be retained in a selected annular groove 59 to adjust the height of the shelf 52. The stopper 58 has opposite surfaces and a diameter smaller than the outer diameter of the tubular members 55, wherein the abutting edges of the adjacent tubular members 55 respectively abut against the opposite surfaces of the stopper 58 so as to form an annular groove 59 in cooperation with the surfaces of the abutting edges of the tubular members 55, the width of which depends on the space between the adjacent tubular members 55 (see FIG. 15). The load tends to be applied over a particular region, and more specifically the abutting regions between the stopper 58 of a smaller diameter and the mutually facing edges of the adjacent tubular members 55. Consequently, the edges of the tubular members 55 or other adjacent portions may be chipped off or deformed.
In consideration of the above problems, a modular shelving unit having a different interconnection arrangement has been proposed, as illustrated in FIG. 16. This arrangement omits the stopper 58 of the interconnecting member 56 to allow the mutually facing edges of the adjacent tubular members 55 to directly contact each other. With this direct abutment of the tub ular members 55, the load applied to one of the tubular members 55 is transferable to the adjacent tubular member 55 for dispersion of the load.
However, the modular shelving unit of this arrangement also has a drawback that, since the interconnection between the tubular members 55 is accomplished by a threaded engagement only, improper positioning of the interconnecting member with regard to the tubular members 55 may occur during screwing operation, which results in unstable interconnection of the tubular members 55, as illustrated in FIG. 17. Such improper positioning or unstable connection can not be corrected even by the abutment between the tubular members 55 and the stopper. This causes the tubular members to slightly tilt sidewards from the axis of each post after they are interconnected together.
The modular shelving unit of the above arrangement in accordance with another prior art design, as shown in FIGS. 18, 19a, and 19b further includes the posts 51, each of which has an uppermost tubular member 55, and a cap 61 forced into an upper end 51a of the upper most tubular member 55 or of each post. Each post 51 of the modular shelving unit also has a lowermost tubular member 55, and an adjustable foot 62 in the form of a connector which is forced into a lower end 51b of the lowermost tubular member 55 or of each post. A caster 63 is optionally mounted to the connector 62 of each post 51.
To form each post 51 according to the above arrangement, at least two tubular members 55, specifically the uppermost and lowermost tubular members 55 are required, since the opposite ends of each post 51 need to be covered by the cap 61 and the connector 62. That is, for the modular shelving unit of a shorter length accommodating only one tubular member 55 for each post 51, and therefore using the uppermost tubular member 55 or the lowermost tubular member 55 for each post, the upper most tubular member 55 without the adjustable foot or the caster 63 may damage a floor with the lower edge 51b, or the post may be damaged by the floor surface. When only the lowermost tubular member 51 is used for each post, a user's cloth, etc., may be accidentally caught on or damaged by the upper edge 51a of the tubular member 51, and an appearance of the unit may be deteriorated. Thus, the modular shelving unit of such a conventional type may lower the flexibility in assembling the unit according to various conditions.
Therefore, an object of the invention is to provide a modular shelving unit that is capable of avoiding the concentration of the load into an interconnecting member interposed between the adjacent tubular members, and the tilting of the post in assembled state, as well as increasing the unit strength to such a degree as to be tolerable against a possible load.
Another object of the invention is to provide a modular shelving unit that is capable of being assembled by flexibly combining the tubular members or selecting a proper number of the tubular members for each post by a user without the limitation of the attaching points for the cap and the adjustable foot.